Method, Telecommunications Node and Telecommunications Terminal

ABSTRACT

The invention relates to a method for establishing a communication service with a user equipment in the coverage area of a base station is disclosed. The base station is part of a telecommunication system comprising a plurality of base stations connected to a core network containing a connection information database. In the method, at least one communication identifier is received by the base station of the user equipment in the coverage area of the base station after the base station has processed information indicative of a disconnection between the base station and the connection information database, e.g. a disconnection between the base station and the core network. The received at least one communication identifier is stored in a local storage associated with the base station. The communication service is established via the base station using the communication identifier from the local storage.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of, and claims priority to,U.S. application Ser. No. 14/651,545, filed on Jun. 11, 2015, which is anational stage entry of, and claims priority to, PCT/EP2013/076644,filed on Dec. 16, 2013, which claims priority to European PatentApplication EP 12197439.8, filed in the European Patent Office on Dec.17, 2012, all three of which are hereby incorporated in their entiretyherein by reference.

FIELD OF THE INVENTION

The invention relates to a method for establishing a communicationservice with a user equipment in the coverage area of a base station ina telecommunication system comprising a plurality of base stationsconnected to a core network containing a connection informationdatabase. The invention also relates to a telecommunications node and atelecommunications terminal for use in such a method.

BACKGROUND

During the last decade, mobile telecommunications has become thepredominant form of communications and further growth is expected in theyears to come. Mobile telecommunications relies on the existence of aradio network providing radio coverage by means of base stations inareas through which mobile terminals can move. The base stations areconnected to a core network of the telecom provider in order to allowcommunication services to be established. The core network comprisesseveral further telecommunications nodes. One such a node, e.g. a HomeLocation Register (HLR), a Home Subscriber System (HSS) or a domain nameserver (DNS), is a central database with communication identifiers thatare required to establish a communication service (e.g. a voice call ora data transfer) with one or more of the mobile terminals as is known inthe art. The central database is part of the core network of the networkprovider.

The existing 3G and 4G telecommunication standards require theavailability of the communication identifiers from the central database(e.g. the HLR or the HSS) to establish a communication service with theterminals in the coverage area of the base station. If the centraldatabase is not available, a communication service cannot beestablished. Such a situation of unavailability of the central databasecommunication identifiers may e.g. arise when a catastrophic eventoccurs (e.g. an earthquake, flooding, explosion) or due to hardware orsoftware failures in the telecommunications system. In one particularexample, the connection link between one or more base stations (that assuch are still able to provide radio coverage for the terminals for oneor more communication services) and the core network may be broken. Inone other example, the connection link with the base station isoperational, but other parts of the core network do not operateappropriately such that the central database cannot be accessed.

In emergency situations, there is a need for communication in therelevant area and if the base stations are still able to provideservices, this capacity is desired to be used to provide communicationservices. Such services may include SMS, location informationprovisioning (e.g. GPS coordinates), e-mail and, if possible, voicecommunication. However, since the central communication identifierinformation database is not available, the existing standards do notallow for these communication services to be established.

SUMMARY

In view of the above, it is desirable to enable communication serviceswith a user equipment in the coverage area of an operative base stationwhen the central database with communication identifiers forestablishing communication services with the user equipment is notavailable. In particular, it is desirable to enable such communicationservices with the user equipment when the connection link between thebase station and the core network fails to operate.

To that end, a method for establishing a communication service with auser equipment in the coverage area of a base station is disclosed. Thebase station is part of a telecommunication system comprising aplurality of base stations connected to a core network containing acommunication identifier database. In the method, at least onecommunication identifier is received by the base station forcommunicating with the user equipment in the coverage area of the basestation after the base station has processed information indicative of adisconnection between the base station and the connection informationdatabase, e.g. a disconnection between the base station and the corenetwork. The received at least one communication identifier is stored ina local storage associated with the base station. The communicationservice is established via the base station using the communicationidentifier from the local storage.

Moreover, a computer program product implemented on a computer-readablenontransitory storage medium is disclosed, wherein the computer programproduct is configured for, when run on a computer, to execute the methoddescribed herein.

Still further, a telecommunications node is disclosed in atelecommunication system comprising a plurality of base stationsconnected to a core network containing a connection informationdatabase. The telecommunications node may comprise a base station. Thetelecommunications node comprises a processor configured for processinginformation indicative of a disconnection between the telecommunicationsnode and the connection information database, e.g. a disconnectionbetween the base station and the core network. The telecommunicationsnode also comprises a receiving system configured for receiving at leastone communication identifier for communicating with a user equipment ina coverage area of a base station of the telecommunications system,after processing information in the telecommunications system that isindicative of a disconnection between the base station and theconnection information database, e.g. a disconnection between the basestation and the core network. The telecommunications node comprises astorage, associated with the telecommunications node, for storing thereceived communication identifier and for providing the communicationidentifier enabling a communication service to be established with theuser equipment.

Finally, a telecommunications terminal (e.g. a user equipment UE) isdisclosed that is configured for use with the telecommunications node.The terminal comprises a receiving system, a processor and atransmission system. The receiving system is configured for receiving adisconnection indication indicating a disconnection between a basestation and the connection information database, e.g. a disconnectionbetween the base station and the core network. The processor isconfigured for processing the disconnection indication and makingavailable at least one communication identifier and, optionally, furtheremergency help relevant information, in response to receiving thedisconnection indication. The transmission system is configured fortransmitting the at least one communication identifier and, optionally,the further information.

By providing a local database associated with a telecommunications node,such as a base station, wherein the local database contains at least onecommunication identifier of the user equipment, the base station thathas access to the local storage can access the communication identifier(and, possibly, information associated with that communicationidentifier) when needed to establish a communication service associatedwith that communication identifier without requiring access to thecentral database. The base station or base stations are able to providean operative radio network in an isolated mode. In other words, when forsome reason, a connection with the central database cannot be made,wireless communication services can still be provided through the basestation having access to the local storage with regard to user equipmentfor which one or more communication identifiers are stored in the localstorage. When the connection between the base station and the corenetwork is not operative, the local storage provides a means to emulate(part of) the functionality of the core network.

Typical examples of communication identifiers include identifiers forvoice communication services and/or data communication services. Theseidentifiers are user-level communication identifiers, i.e. identifiersthat users typically use to establish a communication service with auser equipment. For example, the communication identifier(s) may includean MSISDN of a user equipment for voice communication services and SMSservices, a SIPURI for SIP communication services, a web address (URL)for internet services, an e-mail address for e-mail services, etc.

It should be noted that the storage of the communication identifiers maybe caused in response to processing the information indicative of thedisconnection. A local database may be generated as a result of thisinformation. Alternatively, an existing local database may be filledwith the communication identifier(s) obtained from communication betweenthe user equipment and the core network before detection of thedisconnection.

It should be appreciated that further core network functionality mayalso be provided at the base station. One example of such functionalityis the issuing of IP addresses for user equipment wanting to establish aPDP context activation procedure as defined in TS 23.060.

Preferably, each base station has its own local storage to optimize thechance that an operative base station can access the local storage. Thelocal storages of separate base stations may exchange information e.g.by synchronisation. This may occur, for example, when a collection ofbase stations is still operative and information exchange (wired orwireless) is possible between the base stations. However, in some cases,multiple base stations may share a local storage. This shared localstorage may reside in either a single or in multiple base stations.

It should also be appreciated that the information indicative of adisconnection between the base station and the central communicationinformation database may be received from an external system informingthe telecommunications node, e.g. the base station(s), of thedisconnection. However, in an embodiment of the invention, theinformation indicative of the disconnection is obtained by the basestation detecting the disconnection between the base station and thecore network. This embodiment enables detecting the disconnection by thebase station without having to rely on external system(s) that may bedamaged or dysfunctional.

Information indicative of a disconnection may comprise the absence ofinformation that would be received in case of an operative connection.For example, the base station may detect the absence of acknowledgementson messages sent to the core network. In that case, the absence of theacknowledgement(s) indicates the disconnection with the core network.

It should also be appreciated that the UE, after having received thedisconnection indication, may skip or adapt certain parts of theprocedure wherein it normally transmits user data or control data. Forexample, the UE may omit applying encryption to at least part of thedata transmitted to the base station, such as the communicationidentifiers and/or the further information as mentioned below. As aresult, the base station receiving the data can simply store the data inthe local storage and the stored data is readily accessible for use bye.g. emergency workers.

The establishment of the communication service using the locally storedcommunication identifiers involves looking up the communicationidentifier in the local database. Information associated with thecommunication identifier may also be retrieved from the local storage,e.g. location information (especially useful when multiple base stationsare still operative) and/or lower level parameters for the userequipment such as IMSI or TIMSI. This information may then be applied toset up the communication service with the user equipment.

An embodiment of the disclosed method comprises transmitting adisconnection indication from the base station to the user equipment inresponse to the information indicative of the disconnection andreceiving the at least one communication identifier in response totransmitting the disconnection indication. The disconnection indicationtriggers the user equipment to transmit one or more of the communicationidentifiers to the base station that would normally not be transmittedto the base station, such as the MSISDN, the SIP URI and/or the e-mailaddress.

The disconnection indication may be transmitted from the base station inresponse to receiving an attach request at the base station from theuser equipment. User equipment typically attempts to attach to thenetwork when switched on or as a result of expiry of a timer triggeringa re-attach.

In order to receive the communication identifier(s) more quickly at thebase station, the disconnection indication may be initiated from thenetwork without waiting for an attach request. The disconnectionindication may e.g. be triggered at the network side as a result ofreceiving or detecting the information indicative of the disconnectionbetween the base station and the central connection informationdatabase, e.g. a disconnection between the base station and the corenetwork. One example of a disconnection indication triggered at thenetwork side may be the inclusion of the disconnection indication in thesystem information that is broadcast in the cell of the base station.Alternatively, another signalling message may be used for the purpose.In response to the network side initiated disconnection indication, theuser equipment may transmit the communication identifier to the basestation, e.g. in an adapted reattach procedure.

In a further embodiment of the method, further information may bereceived from the user equipment at the base station and stored in thelocal storage. The further information may comprise emergency helprelevant information. This information may include information about thelocation of the user equipment (e.g. GPS coordinates measured by theterminal) or information about the battery status of the user equipment.The former information can be used to localize users of the userequipment, whereas the latter can be used to evaluate which userequipment to contact first before the battery is dead.

In order to be able to start establishing communication with userequipment as quickly as possible, an advantageous embodiment of themethod includes the step that, prior to receiving information indicativeof a disconnection between the base station and the connectioninformation database, communication identifiers from one or more of thefurther user equipment are already stored in the local storage. This maybe done in particular for non-encrypted identifiers that pass the basestation. After having processed the information indicative of adisconnection between the base station and the connection informationdatabase, the communication service can be established via the basestation with the further user equipment using the communicationidentifier stored in the local storage for the further user equipment.This embodiment presumes that at least part of the content of the localdatabase of a time interval prior to the disconnection may still bevalid after the disconnection by the base station. It is noted that theinvention relates to all possible combinations of features recited inthe claims. Thus, all features and advantages of the first aspectlikewise apply to the second and third aspects, respectively.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the invention will be explained in greater detail byreference to exemplary embodiments shown in the drawings, in which:

FIG. 1 depicts a simplified prior art telecommunications system and atime diagram illustrating a few basic steps of establishing acommunication service with a user equipment in the prior arttelecommunications system;

FIGS. 2A and 2B are schematic illustrations of a telecommunicationssystem containing a radio network and a core network according to anembodiment of the invention;

FIGS. 3A and 3B are block diagrams of a telecommunications node, e.g. abase station, and a user equipment, respectively, for use in thetelecommunications system according to an embodiment of the invention;

FIGS. 4A and 4B are flow charts for a method of using thetelecommunications node and the user equipment of FIGS. 3A and 3B,respectively;

DETAILED DESCRIPTION

FIG. 1 depicts a portion of a simplified prior art telecommunicationssystem and a time diagram illustrating a few basic steps of establishinga communication service between a user equipment UE-A and a userequipment UE-B in this telecommunications system. The portion of theillustrated simplified telecommunications system comprises a first basestation BTS1 defining a cell providing radio coverage for UE-A and asecond base station BTS2 defining a second cell providing radio coveragefor UE-B. Both base stations BTS1 and BTS2 are drawn to be associatedwith a common mobile switching centre O-MSC (intermediary nodes, such asa base station controller BSC, are not shown). Furthermore, a gatewaymobile switching centre (G-MSC) is shown that has access to a homelocation register HLR.

Whereas FIG. 1 illustrates a 2G circuit switched telecommunicationssystem (e.g. GSM), it should be appreciated that other generations oftelecommunications systems comprise similar core networks. For example,in 3G packet switched systems, a node SGSN is provided (corresponding tothe O-MSC in FIG. 1) and a node GGSN is provided (corresponding to theG-MSC in FIG. 1) that is connected to a HLR. In IMS, a S-CSCF has asimilar function as the O-MSC, and the I-CSCF has a similar function asthe G-MSC. Also, 4G-LTE systems comprise similar entities such asmobility management entities MME and a home subscriber system HSS. Ininternet communication using IP addresses, a DNS performs a role similarto the HSS to translate a URL into an IP address.

The time diagram illustrates the situation wherein the networkestablishes a communication service (e.g. a voice call or an SMS messagetransfer) between user equipment UE-A and user equipment UE-B. It isnoted that in the 2G system standards, the user equipment may also bereferred to as mobile station MS.

In a first step (a), a call setup message is transmitted by UE-Acomprising at least the telephone number MSISDN of UE-B as thecommunication identifier. The call setup message is received by basestation BTS1 and forwarded to the originating MSC (O-MSC) in step (b).The O-MSC searches for the gateway MSC (G-MSC) of the network operatorof the subscriber of UE-B on the basis of the MSISDN received in step(b). Then, in a next step (c), the call setup message is forwarded tothe appropriate G-MSC. The G-MSC consults the home location register(HLR) associated with the G-MSC to find the location of UE-B in step (d)using the MSISDN of UE-B as the key. In the depicted situation, the HLRwill inform the G-MSC that UE-B is also in the area of O-MSC in step (e)and the G-MSC will subsequently inform the O-MSC accordingly in step(f). O-MSC will instruct the base stations BTS1 and BTS2 to transmit apaging signal for UE-B in step (g) and in step (h) the receipt of thepaging signal is illustrated. A communications service may now beestablished between UE-A and UE-B. For example, UE-B may attach to thenetwork in response to receiving the paging signal of step (h) in orderto subsequently receive an SMS message.

As explained above, in order to establish a communication servicebetween UE-A and UE-B in prior art telecommunications systems, thecentral connection information database HLR is consulted in order tolocate the user equipment UE-B. Obviously, if the central databasecannot be accessed (e.g. due to an external event, such as an earthquakeor an explosion or due to hardware/software failure), the communicationsservice cannot be established. Access of the central database HLR maye.g. fail as a result of a broken connection between the BTS's 1 and 2and the core network, as indicated by the crosses in FIG. 1. It shouldbe appreciated, however, that alternatively the connection with thecentral database may also be broken elsewhere in the network.

FIGS. 2A and 2B are schematic illustrations of a 2G, 3G or 4Gtelecommunications system 1 containing a radio network 2 and a corenetwork 3 according to an embodiment of the invention. As illustrated inthe figures, the base stations BTS are isolated from the core network 3.

Basically, in the telecommunications system 1, each of the base stationsBTS is associated with a local database LDB storing communicationidentifiers of user equipment UE in their cells. It should beappreciated that the base stations are referred to as NodeB's in 3Gtelecommunications systems and as eNodeB's in 4G telecommunicationssystems. Preferably, each base station has its own local database LDB,as shown in FIG. 2A. The local databases LDB of the respective basestations BTS may exchange information, e.g. parts or all of theinformation stored, if possible, as shown by the dashed double arrowEXCH in FIG. 2A. This may occur, for example, when a collection of basestations is still operative and information exchange (wired or wireless)is possible between the base stations. Alternatively, two or more basestations BTS share a common local database cLDB, as illustrated in FIG.2B.

FIGS. 3A and 3B are block diagrams of a telecommunications node, e.g. abase station BTS, and a user equipment UE, respectively, for use in thetelecommunications system 1 of FIG. 2A according to an embodiment of theinvention. In the block diagrams, some components for performing thedisclosed method are schematically illustrated. It should be noted thatthese components may be implemented in hardware, software or in a hybridfashion. The telecommunications node BTS and the user equipment UE atleast contain a processor uP for executing actions, a controller CTRLfor controlling actions by the processor uP and one or more forms ofstorage (not shown) for storing computer programs and (intermediate)processing results.

The base station BTS furthermore comprises a transceiver Tx/Rx for radiocommunication with user equipment UE in the cell of the base stationBTS.

Moreover, the base station BTS contains the associated local databaseLDB for storing communication identifiers.

The base station BTS also contains a detector DET for monitoring theconnection with the core network 3. Detector DET may e.g. detect theabsence of acknowledgements normally received from the core network.Detector DET is connected to controller CTRL in order to signal a brokenconnection with the core network 3 as indicated by the cross in FIG. 3A.Controller 3 may then instruct the processor uP to perform theappropriate actions as will be discussed in more detail with referenceto FIGS. 4A and 4B. It should be noted that, instead of monitoring theconnection with the core network, detector 3 may also provide aninterface, possibly a radio interface 4, to an external system that canalert the base station BTS of the dysfunctional core network or of theunavailability of the central database HLR.

FIG. 3B is schematic illustration of a user equipment UE. The UEcomprises a transceiver Tx/Rx for communication over the radio interfacewith the base station BTS of FIG. 3A. The UE comprises a battery BAT forpower.

The UE comprises a memory storing communication identifiers, such as theMSISDN of the UE, an e-mail address of an e-mail account available viathe UE, a SIP URI for SIP data sessions with the UE etc.

The UE also contains a GPS module for determining location coordinatesof the UE.

An embodiment of operating a base station BTS and a user equipment UE inthe telecommunications system of FIG. 2A. will now be described in moredetail with reference to FIG. 4A. FIG. 4A is a flow chart for a methodof using the base station BTS and the user equipment UE of FIGS. 3A and3B.

FIG. 4A illustrates an embodiment of a base station initiateddisconnection indication.

In a first step S1, the detector DET of the base station BTS detects adisconnection with the core network 3. In response to detecting thedisconnection, this disconnection information is processed by issuing aninstruction in step S2 from controller CTRL to processor uP to transmita disconnection indication in the cell of the base station BTS. In stepS3, base station BTS transmits the disconnection indication in the cell.The base station BTS may e.g. set an emergency operation bit in thebroadcast system information block or transmit another signallingmessage. In step S4, the user equipment UE receives the disconnectionindication. The disconnection indication forces the user equipment UE toretrieve one or more communication identifiers from the memory under thecontrol of controller CTRL of the UE in step S5. For example, readingthe emergency operation bit in the system information block on thebroadcast channel (or another signalling message on another channel) bythe UE, triggers the UE to cooperate in a new attach procedure and toprovide its communication identifier(s) to the base station. Optionally,in step S6, the disconnection indication may also trigger retrieval offurther information, e.g. emergency help relevant information, such aslocation coordinates provided by a the GPS module and/or the batterystatus of the battery BAT. For example, the emergency bit may triggertransmitting the GPS position of the UE, information about the batterystatus, etc. Also, interaction with the user of the UE can be triggered,e.g. by requesting manual input on e.g. the health status of the userand/or other people.

The transmission of the disconnection indication could also force callsoriginating from UE's in the cell to be routed to a predeterminedtermination point, e.g. local rescue workers.

In step S7, the communication identifier(s) and, optionally, the furtherinformation, is transmitted from the UE to the base station BTS inresponse to receiving the disconnection indication and is received atthe base station BTS in step S8.

In step S9, the communication identifiers and, optionally, the furtherinformation, is stored in the local database LDB associated with thebase station BTS.

FIG. 4B is flow chart of an alternative embodiment, wherein thetransmission of the disconnection indication is triggered from the sideof the user equipment UE.

Again, in a first step S1, the detector DET detects a disconnection ofthe base station BTS with the core network 3.

A user equipment may periodically send a re-attach request to thetelecommunications network 1, e.g. as a periodic location area update asspecified in 3GPP TS 24.301. The UE may also send an attach requestafter being switched on. The UE typically sends a re-attach requestafter expiry of a timer. Step S10 represents the transmission of anattach or re-attach message from the user equipment UE. In step S11, theattach or re-attach message is received at the base station BTS. Thetime interval between time at which the disconnection is detected andthe receipt of the attach or re-attach request depends e.g. on theexpiry of the timer and may be different for different UE's in thenetwork.

After receiving the attach request, the controller in the base stationBTS instructs the processor to transmit a disconnection indication instep S2 followed by the actual transmission of the disconnectionindication in step S3. The remainder of the method follows steps S4-S9as indicated in FIG. 4A.

In the case of using a regular, periodic attach update procedure, uponreception of the attach request in step S11, the base station BTS maye.g. respond with an error code or set a disconnection flag, e.g. anemergency mode operation flag. By interpretation of the error code ordisconnection flag, the UE is then instructed to follow a disconnectedstate procedure, e.g. for emergency operation. Hence, the UE wouldrespond by sending the communication identifier(s) and, optionally, thefurther information. The communication identifier and furtherinformation may then be stored in the local database LDB of the basestation BTS.

After storage of the connection identifier in the local database LDB ofthe base station, the primary means for establishing the communicationservice with the user equipment in the cell of the base station isavailable. Further information, not relevant to the invention, may beneeded to establish the communication service. As an example, the userequipment may set up an IP connection, wherein the user equipmentobtains an IP address from the base station. The local database may havestored the relation between the communication identifier and theassigned IP address, such that the base station has information which IPconnection should be used for which communication identifier. In anotherexample, the local storage stores the location of the UE, e.g. in whichcell(s) the UE is. After receiving a communication request for aparticular communication identifier (e.g. an MSISDN), a paging messageis transmitted in the cells where the UE is known to be according to theinformation in the local database. The local database LDB may then alsostore temporary identifiers of the UE assigned when the UE was attachedto the network.

In the preceding description, it has been assumed that the localdatabase LDB at the telecommunications node was empty and was filledafter detection of the disconnection by procedures described withreference to FIGS. 4A and 4B. However, it may be useful to intercept oneor more communication identifiers and, optionally, further informationprior to detecting the disconnection, such that the local database isalready filled with the one or more communication identifiers and,possibly, the further information. This embodiment provides for a quickstart of filling the local database LDB with communication identifiersafter the detection of the disconnection. At least some of thecommunication identifiers of UE's may still be relevant after thedetection of the disconnection. The communication identifier(s) and/orfurther information preferably only relate to non-encrypted identifiersand information, since decryption keys will normally not be available atthe base station BTS.

It is noted that the method has been described in terms of steps to beperformed, but it is not to be construed that the steps described mustbe performed in the exact order described and/or one after another. Oneskilled in the art may envision to change the order of the steps and/orto perform steps in parallel to achieve equivalent technical results.

With some modifications, one skilled in the art may extend theembodiments described herein to other architectures, networks, ortechnologies.

Various embodiments of the invention may be implemented as a programproduct for use with a computer system or a processor, where theprogram(s) of the program product define functions of the embodiments(including the methods described herein). In one embodiment, theprogram(s) can be contained on a variety of non-transitorycomputer-readable storage media (generally referred to as “storage”),where, as used herein, the expression “non-transitory computer readablestorage media” comprises all computer-readable media, with the soleexception being a transitory, propagating signal. In another embodiment,the program(s) can be contained on a variety of transitorycomputer-readable storage media. Illustrative computer-readable storagemedia include, but are not limited to: (i) non-writable storage media(e.g., read-only memory devices within a computer such as CD-ROM disksreadable by a CD-ROM drive, ROM chips or any type of solid-statenon-volatile semiconductor memory) on which information is permanentlystored; and (ii) writable storage media (e.g., flash memory, floppydisks within a diskette drive or hard-disk drive or any type ofsolid-state random-access semiconductor memory) on which alterableinformation is stored.

It is to be understood that any feature described in relation to any oneembodiment may be used alone, or in combination with other featuresdescribed, and may also be used in combination with one or more featuresof any other of the embodiments, or any combination of any other of theembodiments. Moreover, the invention is not limited to the embodimentsdescribed above, which may be varied within the scope of theaccompanying claims.

1. A method for establishing a communication service with a userequipment in the coverage area of a base station in a telecommunicationsystem comprising a plurality of base stations connected to a corenetwork containing a connection information database, the methodcomprising the steps of: receiving at least one communication identifierfor communicating with the user equipment in the coverage area of thebase station, after processing information indicative of a disconnectionbetween the base station and the connection information database, e.g. adisconnection between the base station and the core network, by the basestation; storing the received communication identifier in a localstorage associated with the base station; establishing the communicationservice with the user equipment via the base station using thecommunication identifier from the local storage.